Apple Computer executives took the stage yesterday in San Francisco in an effort to rev up visitors to MacWorld Expo, the four-day convention at the Moscone Center this week. But news of a major management bloodletting, impending layoffs and a possible takeover cast a pall over the festivities.

Jim Buckley, president of Apple Americas, echoed a question many analysts and some of the Macintosh faithful had wondered over the past year. "Will there be an Apple Computer?" he asked. "Scary question."

Buckley, the company's No. 2, portrayed Apple as a buoyant survivalist with great support from its customers and developers.

While Buckley spread the gospel at the Moscone Center, the curtain went up on widespread management departures.

An Apple Computer spokeswoman and other sources confirmed the shakeup at the vice president level. Barbara Krause, vice president of corporate communications and one of Apple's highest ranking women, is leaving to start her own public relations firm.

Satjiv Chahil, formerly the vice president of entertainment and new media, will be senior vice president of corporate marketing. He will report to Michael Spindler, the company's president and chief executive.

Spindler was at MacWorld, said a spokeswoman, but had no speaking engagements.

The recent management upheaval comes just months after four top executives -- including Joseph Graziano, the company's chief financial officer and Dan Eilers, the top marketing executive -- left the company. According to sources, the management turmoil will spread to other departments such as finance.

Company-wide layoffs are expected after January 17 when Apple releases its quarterly earnings. Apple's board of directors headed by A.C. (Mike) Markkula Jr. is expected to meet in two weeks. As the exodus of top people seems to be growing, sources speculated that Apple's results for the quarter, which ended December 31, could be even worse than the company predicted.

Last month Apple warned that instead of earning 78 cents per share for the quarter, as Wall Street had estimated, it would post a loss for the three-month period. That news sent Apple's stock into a tailspin, losing more than 15 percent in two days.

Such uncertainty overshadowed the more than 1,000 developers, Mac enthusiasts and business partners who listened to Buckley's keynote speech and watched demonstrations of Apple's latest technology.

But Buckley's message was more spiritual than technical.

"When I hear the question about Apple's future -- and I hear it frequently -- I have to remember that question was also asked in 1978 and 1981 and 1985 and 1993," Buckley said. "But you know what? We're still here, and there are more Macintoshes out there than ever before."